Black Ash

(Fraxinus nigra)

Status: Endangered (ESA 2022), Threatened (COSEWIC 2018)

Table of Contents:

Species Identification
Habitat and Biology
Threats/Reasons for Being at Risk
Conservation and Recovery Strategies
Why You Should Care
How You Can Help

Species Identification:

The Black Ash is a medium-sized, shade intolerant, hardwood deciduous tree that grows to about 20 m tall. It has thick, opposite branches that angle upwards forming a narrow, rounded crown. It has compound leaves made of 7, 9, or 11 deep green oval-shaped leaflets, and the leaflets arranged in an opposite pattern, with one leaflet at the end of the leaf stalk. Black Ash have light grey bark that is soft and corky when they are young and becomes scaly with age. Flowers appear just before leaf emergence and are small and grouped in clusters. The fruit is composed of flattened, papery tissue with a broad elliptical wing.

Habitat and Biology:

51% of the global range of the Black Ash is in Canada, and 25% is in Ontario. The Canadian range of Black Ash extends from Newfoundland to Manitoba, and they are found everywhere in Ontario except the far north. Black Ash trees are found throughout The Land Between. They are also found from North Dakota south to Iowa, Illinois, Virginia, and Delaware.

The Black Ash is a flood-tolerant species and most commonly occurs in areas of moist, nutrient-rich soils such as swamps. Black Ash is a slow-growing tree that lives up to 150 years and reaches maturity after 30 to 40 years. The Black Ash produces seeds every 1-8 years, and seeds will remain dormant for 2-8 years before germinating. Flowers are pollinated by the wind and it is one of the last trees to produce leaves in the spring, and one of the first to drop its leaves in the fall.

Map taken from Government of Canada: https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/black-ash-2018.html#toc5

Threats/ Reasons for being at Risk:

1. Emerald Ash Borer: The Emerald Ash Borer is an invasive Asian beetle that lives out its life cycle on Ash trees, including the Black Ash. The Emerald Ash Borer feeds on the leaves, bark and wood. The larvae tunnel through and feed on the wood and internal tissue of the tree, disrupting its nutrient transportation systems and eventually causing death. Detection of the pest is usually only possible one year or more after infestation, usually when it is too late. The spread of this beetle is predicted to continue as a result of the natural flight of the adult beetles, and as a result of the movement of ash products such as firewood. 90% mortality rates of Black Ash are predicted, with 73% of the Canadian population predicted to be affected in one 60-year generation.

2. Deforestation: Deforestation resulting in the loss or alteration of the wet forested habitat that is favoured by Black Ash also poses a threat to the species. Black Ash is also not a major source of timber or pulp in Canada, but a great deal of trees are still cut down in the commercial forest harvesting industry.

3. White-tailed Deer browsing: There are abundant White-tailed Deer populations throughout Canada and the United States which have an impact on many deciduous tree saplings since they are a preferred food source for White-tailed Deer. Large populations of White-tailed Deer are considered a natural limiting factor for the Black Ash and have caused dramatic declines of saplings.

4. Climate change: The shallow roots of the Black Ash make it prone to being knocked over in strong winds. Climate change has caused increasingly severe weather events like storms and high winds. Climate warming is also beginning to change forest compositions, and severe droughts can change the preferred wet habitat of the Black Ash.

Conservation and recovery strategies:

The main threat to the Black Ash tree population is the Emerald Ash Borer. Multiple innovative traps and lures have been developed by scientists and forestry companies that are now commercially available. These traps and lures allow for early detection of Emerald Ash Borer, so that actions can be taken before the pest has a chance to become established in its host. Parasitic wasps have also been cultivated and used as a natural form of pest control for the Emerald Ash Borer. Alternative pesticides have been explored, including spores of pathogenic fungi. The spores are applied to the Emerald Ash Borer when it enters a trap, and are subsequently transferred to other individuals during mating. Seeds of hardy individuals are being collected to be used to re-establish decimated populations that have been impacted by the Emerald Ash Borer or from harvesting.

Why You Should Care:

There have already been reported occurrences of the Emerald Ash Borer in The Land Between.
The Black Ash is one of only 126 trees native to Canada. Its global or regional loss would have a significant impact on the overall native biodiversity of our province and our country as a whole.
The cost of treatment and/or removal of trees infected by the Emerald Borer is predicted to cost Canadian municipalities up to 2 Billion dollars over a 30 year period. That is a significant portion of your tax dollars!

How can you help?

Learn how to identify Black Ash and submit observations online to The Land Between and/or to iNaturalist.
Do not transfer firewood of any sort, including Black Ash. Burn it where you buy or cut it. This will help limit the spread of the Emerald Ash Borer to other, potentially unaffected areas of Ontario.
Educate yourself in how to identify trees potentially infected by Emerald Ash Borer, and report any potentially infested trees to The Land Between.
Advocate for your municipality or township to invest in Emerald Ash Borer traps to allow for early detection.

Additional Resources:

Government of Ontario’s Black Ash Species at Risk page
Learn how to ID Black Ash from iNaturalist
COSEWIC 2018 Assessment and Report on the Black Ash
Nature Ontario’s Ten Reasons to Demand Immediate Protection for the Endangered Black Ash blog

Sources:

Government of Ontario. 2014. Black Ash. Retrieved from: https://www.ontario.ca/page/black-ash

Hurlburt, D. 2011. Provincial (Nova Scotia) Status Report on Black Ash Fraxinus nigra. Nova Scotia Department of Natural Resources. Retrieved from: https://novascotia.ca/natr/wildlife/biodiversity/pdf/Fraxinus_nigra_Provincial_Status_Report.pdf

COSEWIC. 2018. COSEWIC Assessment and Status Report on the Black Ash (Fraxinus nigra) in Canada 2018. Committee on the status of Endangered Wildlife in Canada (COSEWIC). Retrieved from: https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/black-ash-2018.html#toc9

Government of Canada. 2021. Emerald Ash Borer (factsheet). Retrieved from: https://www.nrcan.gc.ca/forests/fire-insects-disturbances/top-insects/13395